Liquid fuel injection pumping apparatus

ABSTRACT

In a rotary distributor fuel injection pump having outlet ports connected to injection nozzles by way or pipelines respectively, accumulator chambers including a plunger slidable in a cylinder and having one end connected to the associated outlet port are provided. The plungers are loaded by springs towards the end of the cylinder connected to the output and the action of the accumulator chambers is to stabilize the pressure existing in the outlet and the pipeline at the end of injection of fuel.

United States Patent Inventor Ivor Fenne Greenlord, England Appl. No. 847,163 Filed Aug. 4, 1969 Patented July 13, 197i Assignee C.A.V. Limlted London, England Priority Aug. 13, l968 Great Britain 38603/68 LIQUID FUEL INJECTION PUMPING APPARATUS l Claln, 1 Dustin Fig.

[1.8. CI 417/540, 123/ l 39.14 Int. Cl .F04b I00, FOZm 39/00 Fleldolsearell 103/21,

[56] Relerences Cited UNITED STATES PATENTS 2,501,073 3/1950 Meitzler l23/l39.l4 X 2,853,947 9/1958 Evans .t 103/21 3,187,733 6/1965 Heintz l23/139.14 3,507,262 4/]970 Stage l23ll39.14

Primary Examiner-Robert M. Walker AttorneyI-Iolman & Stern ABSTRACT: In a rotary distributor fuel injection pump having outlet ports connected to injection nozzles by way or pipelines respectively, accumulator chambers including a plunger slidable in a cylinder and having one end connected to the associated outlet port are provided. The plungers are loaded by springs towards the end of the cylinder connected to the output and the action of the accumulator chambers is to stabilize the pressure existing in the outlet and the pipeline at the end of injection of fuel.

LIQUID FUEL INJECTION PUMPING APPARATUS This invention relates to liquid fuel injection pumping apparatus for supplying fuel to a multicylinder internal combustion engine and of the kind comprising in combination, an injection pump and a rotary distributor member which is arranged to direct liquid fuel expelled from the injection pump during successive injection strokes, to a plurality of outlet ports in turn, the outlet ports being connected respectively to injection nozzles which direct fuel into the cylinders respectively of the engine.

The object of the invention is to provide such an apparatus in a simple and convenient form. According to the invention an apparatus of the kind specified is characterized by the provision ofa plurality of accumulator chambers in communication respectively with the outlet ports, each accumulator chamber comprising a cylinder one end of which is in communication with the associated outlet port and the other end of which is in communication with a lower pressure than the pressure which occurs during the delivery of fuel by the injection pump, the cylinder containing a slidable plunger which is loaded by resilient means towards said one end of the cylinder and the arrangement being such that during the initial delivery of fuel by the injection pump the plunger will be displaced its maximum extent against the action of the resilient means and when the delivery of fuel by the injection pump ceases the pressure at the outlet port will be maintained at a further low pressure by the action of the resilient means.

ln one example of a liquid fuel pumping apparatus in accordance with the invention and as shown in schematic form in the accompanying drawing, there is provided a body part in which is joumalled a rotary cylindrical distributor member ll. At one end of the distributor member there is provided a transversely extending bore 12 in which is accommodated a pair of reciprocable pumping plungers 13. The pumping plungers are arranged to be moved inwardly as the distributor member rotates by the action cam lobes formed in the internal periphery of an annular cam ring 14 which surround the distributor member at this point and which is mounted in the body part. The cam lobes together with the pumping plungers constitute an injection pump from which fuel is expelled during inward movement of the pumping plungers, by way of a longitudinal passage [5 formed in the distributor member and which at one point communicates with a radially extending delivery passage 16. For cooperation with the delivery passage there is formed in the body part, a plurality of outlet ports 17 which in use, are connected respectively by way of pipelines 18 to injection nozzles 19 mounted so as to direct fuel into the cylinders respectively of an associated engine. The distributor member is driven in timed relationship with the engine and during successive injection strokes of the injection pump, fuel is delivered to the outlet ports [7 in turn.

At another point the longitudinal passage is in communication with a plurality of inlet passages 20 which also extend to the periphery of the distributor member and which are arranged to register in turn, with an inlet port 2| formed in the body part. The inlet port is in communication with a source 22 of liquid fuel under pressure and conveniently this is constituted by avane type feed pump the rotary part of which is mounted at the end of the distributor member remote from the transversely extending bore. The feed pump is provided with an inlet which communicates with a source 23 of fuel and an outlet port which is in communication with the aforesaid inlet port by way of an adjustable throttle member 24 whereby the amount of fuel which flows through the inlet port can be controlled. ln known manner, the feed pump is provided with a relief valve (not shown) whereby the outlet pressure thereof is controlled.

In in operation. during inward movement of the pumping plungers l3the delivery passage 16 is in communication with an outlet port I7 and fuel is expelled from the transverse bore tothe outlet port and flows by way of the interconnecting pipeline. to the associated nozzle 19. At the end of the inward movement of the pumping plungers delivery of fuel to the engine ceases and the cam lobes are so shaped as to permit slight retraction of the plungers 13 whilst the delivery passage is still in communication with the outlet port. In this manner a small quantity of fuel is allowed to flow from the outlet port into the passages of the distributor and this permits rapid closing of the valve which is contained within the injection nozzle 19. During continued rotation of the distributor member the delivery passage I6 is moved out of register with the outlet port and an inlet port 20 moves into register with the inlet port 2!. Whilst this latter communication is established fuel flows from the outlet of the feed pump 22 into the transversely extending bore and the pumping plungers are moved outwardly. The amount of fuel which flows is controlled by the throttle member 24 the setting of which can be adjusted by an operator so that the speed of the associated engine is controlled. During continued rotation of the distributor member the plungers are again moved inwardly whilst the delivery passage in communication with another outlet port. In this manner fuel is supplied to the engine cylinders in turn.

When such apparatus is in use it has been found that small discrepancies occur in the amount of fuel which is delivered by each injection nozzle. It is thought that these discrepancies occur due to the presence of pressure waves in the outlet ports and pipelines. in order to minimize the effect of these pressure waves there is provided in association with each outlet port, an accumulator chamber which comprises a cylinder 15 one end of which is in communication with the outlet port 17 and the other end of which is at a lower pressure than the pressure which occurs during the delivery of fuel by the injection pump. Conveniently this may be atmospheric pressure or it may be the inlet pressure of the feed pump. Mounted within the cylinder is a slidable plunger 26 which is located by resilient means in the form of a coiled compression spring 27 towards said one end of the cylinder and the arrangement is such that during the initial delivery of fuel by the injection pump the plunger will be displaced its maximum extent against the action of the resilient means, whereafter delivery offuel through the pipeline I8 and the nozzle 19 will occur. At the end of the injection stroke, the plunger 26 remains in the aforesaid position until unloading of fuel has ceased and when the pressure of fuel in the outlet port and the pipeline falls to a sufficiently low value, the plunger 26 will be moved by the action of the spring 27 and the accumulator chamber will act to damp any pressure waves which occur in the outlet port and associated pipeline The extent of movement of the plunger 26 against the action of the spring 27 is limited by abutment of a peg on the plunger with the end ofthe cylinder.

Having thus described my invention whatl claim as new and desire to secure by Letters Patent is:

1. A liquid fuel injection pumping apparatus for supplying fuel to a multicylinder internal combustion engine and of the kind comprising in combination, a body part, an injection pump mounted in the body part and operable in synchronism with the associated engine. a plurality of outlet ports formed in the body part and which, in use, are connected respectively to injection nozzles which direct fuel into the cylinders of the engine, a rotary distributor member mounted in the body part, a passage in the distributor member, said passage opening onto the periphery of the distributor member at a position to register with the outlet ports in turn during successive injection strokes of the injection pump, the passage also communicating with the injection pump, the apparatus being characterized by a plurality of accumulator chambers communicating respectively with the outlet ports, each accumulator chamber comprising a cylinder one end of which is in communication with the associated outlet port and the other end of which is in communication with a lower pressure than the pressure which occurs in the outlet port during the delivery of fuel by the injection pump. a slidable plunger within the cylinder, resilient means acting on said plunger to urge the plunger towards said one end of the cylinder and the arrangement being such that during the initial delivery of fuel of the injection pump to an of fuel by the injection pump ceases the pressure a! the outlet port will be maintained at a further low pressure by the action of the resilient means. 

1. A liquid fuel injection pumping apparatus for supplying fuel to a multicylinder internal combustion engine and of the kind comprising in combination, a body part, an injection pump mounted in the body part and operable in synchronism with the associated engine, a plurality of outlet ports formed in the body part and which, in use, are connected respectively to injection nozzles which direct fuel into the cylinders of the engine, a rotary distributor member mounted in the body part, a passage in the distributor member, said passage opening onto the periphery of the distributor member at a position to register with the outlet ports in turn during successive injection strokes of the injection pump, the passage also communicating with the injection pump, the apparatus being characterized by a plurality of accumulator chambers communicating respectively with the outlet ports, each accumulator chamber comprising a cylinder one end of which is in communication with the associated outlet port and the other end of which is in communication with a lower pressure than the pressure which occurs in the outlet port during the delivery of fuel by the injection pump, a slidable plunger within the cylinder, resilient means acting on said plunger to urge the plunger towards said one end of the cylinder and the arrangement being such that during the initial delivery of fuel of the injection pump to an outlet port, the plunger of the accumulator chamber associated with the port, will be displaced its maximum extent against the action of the resilient means and when the delivery of fuel by the injection pump ceases the pressure at the outlet port will be maintained at a further low pressure by the action of the resilient means. 